The occurrence of plate tectonic processes on Earth during the Paleoproterozoic is supported by ca. 2.2–1.8 Ga subduction-collision orogens associated with the assembly of the Columbia-Nuna supercontinent. Subsequent supercontinent breakup is evidence by global ca. 1.8–1.6 Ga large igneous provinces. The North China craton is notable for containing Paleoproterozoic orogens along its margins, herein named the Northern Margin orogen, yet the nature and timing of orogenic and extensional processes of these orogens and their role in the supercontinent cycle remain unclear. In this contribution, we present new field observations, U-Pb zircon and baddeleyite geochronology dates, and major/trace-element and isotope geochemical analyses from the northern margin of the North China craton that detail its Paleoproterozoic tectonic and magmatic history. Specifically, we record the occurrence of ca. 2.2–2.0 Ga magmatic arc rocks, ca. 1.9–1.88 Ga tectonic mélange and mylonitic shear zones, and folded lower Paleoproterozoic strata. These rocks were affected by ca. 1.9–1.8 Ga granulite-facies metamorphism and ca. 1.87–1.78 Ga post-collisional, extension-related magmatism along the cratonal northern margin. We interpret that the generation and emplacement of these rocks, and the coupled metamorphic and magmatic processes, were related to oceanic subduction and subsequent continent-continent collision during the Paleoproterozoic. The occurrence of ca. 1.77–1.73 Ga mafic dykes and ca. 1.75 Ga mylonitic shear zones along the northern margin of the North China craton may have been related to a regional mantle plume event. Our results are consistent with modern style plate tectonics, including oceanic subduction-related plate convergence and continent-continent collision, operating in the Paleoproterozoic. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1029/2022GC010662

Paleoproterozoic Plate Tectonics Recorded in the Northern Margin Orogen, North China Craton

The occurrence of plate tectonic processes on Earth during the Paleoproterozoic is supported by ca. 2.2–1.8 Ga subduction‐collision orogens associated with the assembly of the Columbia‐Nuna supercontinent. Subsequent supercontinent breakup is evidence by global ca. 1.8–1.6 Ga large igneous provinces. The North China craton is notable for containing Paleoproterozoic orogens along its margins, herein named the Northern Margin orogen, yet the nature and timing of orogenic and extensional processes of these orogens and their role in the supercontinent cycle remain unclear. In this contribution, we present new field observations, U‐Pb zircon and baddeleyite geochronology dates, and major/trace‐element and isotope geochemical analyses from the northern margin of the North China craton that detail its Paleoproterozoic tectonic and magmatic history. Specifically, we record the occurrence of ca. 2.2–2.0 Ga magmatic arc rocks, ca. 1.9–1.88 Ga tectonic mélange and mylonitic shear zones, and folded lower Paleoproterozoic strata. These rocks were affected by ca. 1.9–1.8 Ga granulite‐facies metamorphism and ca. 1.87–1.78 Ga post‐collisional, extension‐related magmatism along the cratonal northern margin. We interpret that the generation and emplacement of these rocks, and the coupled metamorphic and magmatic processes, were related to oceanic subduction and subsequent continent‐continent collision during the Paleoproterozoic. The occurrence of ca. 1.77–1.73 Ga mafic dykes and ca. 1.75 Ga mylonitic shear zones along the northern margin of the North China craton may have been related to a regional mantle plume event. Our results are consistent with modern style plate tectonics, including oceanic subduction‐related plate convergence and continent‐continent collision, operating in the Paleoproterozoic.

Greenschist facies metabasite (chlorite schist) and metasediments (banded iron formation (BIF)) in the Wutai Complex, North China Craton recorded extensive fluid activities during subduction-related metamorphism. The pervasive dolomitization in the chlorite schist and significant dolomite enrichment at the BIF–chlorite schist interface support the existence of highly channelized updip transportation of CO2-rich hydrothermal fluids. Xenotime from the chlorite schist has U concentrations of 39–254 ppm and Th concentrations of 121–2367 ppm, with U/Th ratios of 0.11–0.62, which is typical of xenotime precipitated from circulating hydrothermal fluids. SHRIMP U–Th–Pb dating of xenotime determines a fluid activity age of 1.85 ± 0.07 Ga. The metasomatic dolomite has δ13CV-PDB from −4.17‰ to −3.10‰, which is significantly lower than that of carbonates from greenschists, but similar to the fluid originated from Rayleigh fractionating decarbonation at amphibolite facies metamorphism along the regional geotherm (~15 °C/km) of the Wutai Complex. The δ18OV-SMOW values of the dolomite (12.08–13.85‰) can also correspond to this process, considering the contribution of dehydration. Based on phase equilibrium modelling, we ascertained that the hydrothermal fluid was rich in CO2, alkalis, and silica, with X(CO2) in the range of 0.24–0.28. All of these constraints suggest a channelized CO2-rich fluid activity along the sediment–basite interface in a warm Paleoproterozoic subduction zone, which allowed extensive migration and sequestration of volatiles (especially carbon species) beneath the forearc.

https://www.mdpi.com/2075-163X/11/7/748/pdf

Channelized CO2-Rich Fluid Activity along a Subduction Interface in the Paleoproterozoic Wutai Complex, North China Craton

Ultrahigh temperature metamorphism recorded in the Lüliang Complex, Trans-North China Orogen: P–T–t evolution and heating mechanism

The Sulu orogenic belt, formed by the collision between Sino-Korean and South China blocks, has important geological implications due to its unique tectonic setting. To understand the deep crustal structure of the extension of the Sulu orogenic belt in the Yellow Sea, we presented a 220-km long active-source ocean-bottom seismometer wide-angle reflection/refraction profile across the Yellow Sea. The obtained P-wave velocity structure exhibits significant horizontal and vertical variations. The middle and upper crustal regions of the north beneath the survey line exhibit a higher velocity and larger thickness than those of the south, whereas the opposite is the case with the lower crust. The lower crustal high-velocity zone in the Northern Depression of the South Yellow Sea Basin is a manifestation of the mantle material upwelling and accretion to the lower crust. Magmatic intrusions occurred along the faults and formed a high-velocity zone in the middle and upper crusts. Due to undulating Moho interface and varying crustal velocities, the Qingdao–Rongcheng fault is identified as a fault in the Sulu orogenic belt without the significance of tectonic zoning. This study shows that the Sino-Korean Block, Sulu orogenic belt and South China Block are bounded by the Jimo–Muping faults (an extension to the sea), Qianliyan fault and deep fault of the South Yellow Sea. Furthermore, the Sulu orogenic belt may have been formed by the northward subduction of the South China Block beneath the Sino-Korean Block during the Indosinian orogeny to the east of the Shandong Peninsula. 

P‐wave velocity structure of the Sulu orogenic belt in the Yellow Sea, East China: Evidence from wide‐angle ocean bottom seismograph data

Phase equilibria modelling and zircon U-Pb geochronology of Paleoproterozoic mafic granulites from the Chengde Complex, North China Craton

Lithium mineralization during evolution of a magmatic–hydrothermal system: Mineralogical evidence from Li-mineralized pegmatites in Altai, NW China

Petrogenesis of Mo-associated Mesozoic granitoids on the Jiaodong Peninsula: Implications for crustal architecture and Mo mineralization along the Dabie–Sulu Orogen

Corrigendum to “Lithium mineralization during evolution of a magmatic–hydrothermal system: Mineralogical evidence from Li-mineralized pegmatites in Altai, NW China” [Ore Geol. Rev. 149 (2022) 105058]

A unique saline lake sequence in the eastern Tethyan Ocean in responses to the Palaeocene-Eocene thermal maximum: A case study in the Kuqa Depression, Tarim Basin, NW China

H. Zhang

Papers

Phase equilibria modelling and zircon U-Pb geochronology of Paleoproterozoic mafic granulites from the Chengde Complex, North China Craton

Lithium mineralization during evolution of a magmatic–hydrothermal system: Mineralogical evidence from Li-mineralized pegmatites in Altai, NW China

Petrogenesis of Mo-associated Mesozoic granitoids on the Jiaodong Peninsula: Implications for crustal architecture and Mo mineralization along the Dabie–Sulu Orogen

Corrigendum to “Lithium mineralization during evolution of a magmatic–hydrothermal system: Mineralogical evidence from Li-mineralized pegmatites in Altai, NW China” [Ore Geol. Rev. 149 (2022) 105058]

A unique saline lake sequence in the eastern Tethyan Ocean in responses to the Palaeocene-Eocene thermal maximum: A case study in the Kuqa Depression, Tarim Basin, NW China